Cmar_a_280470 319..327

*These authors contributed equally to this work Purpose: The efficacy of primary site surgery in patients with de novo stage IV breast cancer remains controversial. However, few real-world studies have evaluated the benefits of local surgery on the primary site of stage IV breast cancer in China. The purpose of this study was to investigate the role of local surgery in the de novo stage IV breast cancer. Materials and Methods: Women with metastatic breast cancer at diagnosis were identified from Guangxi medical university cancer hospital (China) database from 2009 to 2017. The clinical and tumor features, surgical treatment, and survival rates were compared between surgical and non-surgical patients. Results: Two hundred forty-three patients were included, of whom 125 underwent primary site surgery. Patients who underwent surgery were more often had small primary tumors, fewer lymph node metastases, and had less visceral involvement. Patients in the surgery group had dramatically longer OS (median 35 vs 22 months, log-rank P=0.006). Stratified survival analysis showed that patients with bone metastasis alone or ≤3 metastasis benefit from surgery, while patients with visceral metastasis did not benefit from surgery. In multivariate analysis, surgical treatment, estrogen receptor status, progesterone receptor status and visceral metastases remained independent factors for survival. Conclusion: Surgical resection of the primary site can improve survival in selected de novo stage IV breast cancer patients.